Effect Of Intense Laser Field Research Articles

Controlling the interband transitions in a triple quantum ring: Effects of intense laser and electric fields

In this paper, we theoretically studied the interband transitions in a three-dimensional structure of GaAs/Al0.3Ga0.7As triple concentric quantum rings approximating a reported experimental case. An intense non-resonant laser field and/or a static electric field were appropriately chosen to investigate the heavy-hole spectra and the interband transitions. For the combined actions of the two fields acting in the horizontal plane of the structure, we considered parallel and perpendicular directions. In each study, the effects on the heavy-hole energy spectra were discussed concerning their relationship with wave function localization. The radiative recombination energies, overlap integrals, and interband transition lifetime emphasize regions of interest for efficient control of the radiative decay, which is important for practical applications.

Combined Effects of Intense THz Laser Field and Applied Electric Field on Binding Energy of Exciton in GaAs/GaAlAs Finite Spherical Quantum Dot

This paper describes the combined effects of intense THz laser field and electric field on the ground state binding energy of heavy hole excitons confined in GaAs/ GaAlAs spherical finite quantum dots. The formulation is based on the model of “laser dressed potential” which combines Coulomb interaction and field effect in only one potential as reported in the literature. The calculation is performed by using the variational method in the framework of the single band effective mass theory. Our results show that (i) the laser field increases the electron and hole confinement energy that form the exciton in the QD until they reach a maximum, then they become almost constant for an intense laser field, (ii)the electric field and the laser field lowers the binding energy for all quantum dot radii making the exciton stabilized and clustered near the center of the dot, and iii)the laser field increases the spatial extension of exciton but the electric field decreases it linearly.

Intense Laser Field Effect on the Photo-Ionization Cross-Section of the First Exciton Transition in a Core/Shell Quantum Dot Submitted to an Applied Electric Field

In the current work, we study the intense laser pulse influences on the behaviors of the first excitonic transition in a core/shell quantum dot submitted to an electric field. Therefore, the exciton binding energy and the mean distance between the correlated electron–hole pair are discussed, considering the electric field and laser strength. Our calculations show that both external fields play significant repulsive effects. Through their effects, they oppose the attractive nature of the Coulomb potential between the correlated pair, which decreases the excitonic binding energy. We also analyze the dissociation process by determining the photo-ionization cross-section (PICS). Our findings show that the peaks of the PICS redshift when the shell thickness b−a increases. For a given core radius, the laser and electric field induce a shift toward the low-energy region for the PICS; this displacement is more pronounced for the laser case. Our study also compares simple quantum dots and core/shell quantum dots to show the effect of the inner radius on the obtained results. Our theoretical results can lead to promising applications of exciton-based devices controlled by sizes and external fields.

Nonlinear absorption coefficient and relative refractive index change for Konwent potential quantum well as a function of intense laser field effect

Nonlinear absorption coefficient and relative refractive index change for Konwent potential quantum well as a function of intense laser field effect

Combined effects of intense THz laser field and applied electric field on binding energy of exciton in GaAs/ GaAlAs finite spherical quantum dot

Combined effects of intense THz laser field and applied electric field on binding energy of exciton in GaAs/ GaAlAs finite spherical quantum dot

Effects of external perturbations on light absorption by light/heavy hole excitons in a semi-parabolic quantum well

The effects of electric, magnetic, and intense terahertz laser fields on optoelectronic properties are investigated in a GaAs/AlxGa1-xAs semi-parabolic quantum well. The binding energy, exciton light absorption coefficients, interband transition energies, and dipole elements in the matrix are studied within the structure of the parabolic band and effective-mass approximations. The transition energy difference between the ground-state electron energy level and the ground-state heavy hole (light hole) energy level and matrix elements are carried out as functions of external perturbations with a constant well size. The results exhibit that the exciton binding energies of heavy and light holes reduce as long as the laser dressing parameter is larger. The optical absorption of light hole exciton in the system is stronger than the heavy hole exciton. And the excitonic energies, transition energies, and absorption coefficients are much more sensitive and controlled by changing the external perturbations.

In plane magnetic field and intense laser field effects on second harmonic generation of asymmetric AlGaAs/GaAs double quantum well

The optical properties for nano-structured semiconductor systems are of great importance nowadays, due to its possible implementation for the design of efficient optoelectronic devices. It is also well known that external fields can modify the electronic structure, and induce changes the optical properties as well. In particular the asymmetric double quantum well structures are of paramount importance because its wide range on possible configurations and also because are experimentally feasible and well controlled, particularly AlxGa1-xAs/GaAs heterostructures. In this work we report a systematic study on second harmonic generation (SHG) for an asymmetric AlxGa1-xAs/GaAs double quantum well as a function of non-resonant intense laser field and in-plane magnetic field effect. We analyze the energy level behavior as well as the dipole matrix elements as a function of the above mentioned factors that are important for the SHG. We report a particular configuration that optimize the SHG peak, with and without intense laser field effect, as well as magnetic fields, that also tune the SHG.

Investigating the valence-band bound states in GaAs/GaAsSb/GaAs V-shaped quantum wells: The role of intense laser fields and position-dependent effective mass

This theoretical study investigated the valence-band electronic features in GaAs/GaAsSb/GaAs V-shaped quantum wells. Accordingly, an analytical relation has been extended on the position-dependent effective mass in GaAsSb well region as a function of well geometry. The Finite Element Method and the effective mass approximation have been used to investigate the combined effects due to a non-resonant high-frequency intense laser field and an applied electric field. This study considered the effects of geometric and structural parameters on the laser-dressed confining potential profile, bound states, and the corresponding wave functions. The performed studies have shown that the laser-dressing could convert a V-shaped potential profile to a parabolic-like potential and also a single-well to a double-well. The combined effects of intense laser and electric fields have caused a conversion from a symmetric well to a larger and shallower asymmetric structure. It has been found from the valence-band energy levels that pronounced blueshifts and redshifts were obtained in the electromagnetic energy spectrum with increasing the strength of the intense laser and applied electric fields, respectively. The numerical results have indicated that the electronic properties in valence-band quantum wells were modulated according to the purpose through varying the well half-width and the antimony concentration. Such adjustable valence-band-based features can be beneficial in the design and fabrication of the next generation equipment used in the optoelectronic domain.

Investigating the effect of position-dependent effective mass on the valence-band electronic states of GaAs/GaAsSb/GaAs parabolic quantum wells modulated by intense laser fields

This article has theoretically investigated the valence-band electronic properties of GaAs/GaAsSb/GaAs parabolic quantum well structures. To this end, an analytical expression has been developed to describe the position-dependent effective mass in the GaAsSb parabolic well region as a function of well geometry. Simultaneous effects of a non-resonant high-frequency intense laser field and an applied electric field have been studied using the Finite Element Method within the framework of the effective mass approximation. The laser-dressed confinement potential profile, bound states, and the corresponding wave functions have been examined as a function of geometric and structural parameters of GaAsSb well. The obtained numerical findings have shown that the well geometry was modulated to achieve a Gaussian-like profile from a parabolic shape and a double-well structure from a single-well one under intense laser irradiations. Simultaneous effects of intense laser and electric fields have indicated the formation of asymmetric geometric profiles from symmetric quantum well structures. The analysis of valence-band energy states has revealed pronounced blueshifts and redshifts in the electromagnetic energy spectrum, increasing the strength of the intense laser and applied electric fields. Studies have demonstrated that the valence-band electronic features were adjusted to alter the well half-width and the antimony concentration. These tunable valence-band-based properties can be profitable in designing and applying new devices operating in the optoelectronic field.

Effects of Intense Laser Field on Electronic and Optical Properties of Harmonic and Variable Degree Anharmonic Oscillators

In this paper, we calculated the electronic and optical properties of the harmonic oscillator and single and double anharmonic oscillators, including higher-order anharmonic terms such as the quartic and sextic under the non-resonant intense laser field. Calculations are made within the effective mass and parabolic band approximations. We have used the diagonalization method by choosing a wave function based on the trigonometric orthonormal functions to find eigenvalues and eigenfunctions of the electron confined within the harmonic and anharmonic oscillator potentials under the non-resonant intense laser field. A two-level approach in the density matrix expansion is used to calculate the linear and third-order nonlinear optical absorption coefficients. Our results show that the electronic and optical properties of the structures we focus on can be adjusted to obtain a suitable response to specific studies or aims by changing the structural parameters such as width, depth, coupling between the wells, and applied field intensity.

Electronic Transport Properties in GaAs/AlGaAs and InSe/InP Finite Superlattices under the Effect of a Non-Resonant Intense Laser Field and Considering Geometric Modifications.

In this work, a finite periodic superlattice is studied, analyzing the probability of electronic transmission for two types of semiconductor heterostructures, GaAs/AlGaAs and InSe/InP. The changes in the maxima of the quasistationary states for both materials are discussed, making variations in the number of periods of the superlattice and its shape by means of geometric parameters. The effect of a non-resonant intense laser field has been included in the system to analyze the changes in the electronic transport properties by means of the Landauer formalism. It is found that the highest tunneling current is given for the GaAs-based compared to the InSe-based system and that the intense laser field improves the current–voltage characteristics generating higher current peaks, maintaining a negative differential resistance (NDR) effect, both with and without laser field for both materials and this fact allows to tune the magnitude of the current peak with the external field and therefore extend the range of operation for multiple applications. Finally, the power of the system is discussed for different bias voltages as a function of the chemical potential.

Intense laser field effect on the [formula omitted] molecular complex strongly confined in a semiconductor quantum ring: Electronic and optical properties

The present theoretical study is concerned with the behavior of a D2+ molecular complex strongly confined in a semiconductor quantum ring under external probes: intense laser-field radiation and orthogonal electric and magnetic fields. The theoretical calculations were made using finite element method within the effective mass approximation. The effects of the external probes, donor-donor separation and quantum ring geometrical parameters on the D2+ total energy, D2+ binding energy, and D2+ optical response are studied. We show that the laser-field radiation has a great influence on the two fragmentation processes of D2+ and on their essential features: equilibrium length and dissociation energy. The D2+ optical response defined through adsorption coefficient is studied. Laser field radiation may cause red or blue shifts in the adsorption coefficient peak depending on the quantum ring size and donor-donor positions while the magnetic field can induce an optical transparency effect.

Effects of magnetic, electric, and intense laser fields on the optical properties of AlGaAs/GaAs quantum wells for terahertz photodetectors

We investigate optical absorption coefficients and changes in the refractive index in single- and double-step GaAs/AlGaAs quantum wells under the influence of magnetic, electric, and intense laser fields. For single-step quantum wells, increasing the intensity of the external laser and electric fields induces a red-shift in the total optical absorption coefficient and change in the refractive index and increases their amplitudes; however, increasing the magnetic field generates a blueshift in the optical absorption and change in the refractive index. For double-step quantum wells, the transition energy between the ground and first excited state is strongly decreased. In addition, the total optical absorption coefficients and changes in the refractive index incur a blue shift when the electric and magnetic fields are increased and a red-shift with increasing laser fields. Our analysis of coupling matrix elements, probability densities, and energy levels show that intense laser, electric, and magnetic fields can be harnessed to adjust and tune total optical absorption coefficients and refractive indices for terahertz applications.

Intense laser field effect on the nonlinear optical properties of triple quantum wells consisting of parabolic and inverse-parabolic quantum wells

The nonlinear optical rectification, the second harmonic generation coefficient, and the third harmonic generation coefficient in parabolic-inverse parabolic-parabolic quantum wells (PIPPQWs) and inverse parabolic-parabolic-inverse parabolic quantum wells (IPPIPQWs) are calculated varying the intense laser field (ILF) parameter (). The modifications of the dipole moment matrix elements and the energy levels are depending on the potential shape. The results show that the ILF intensity exerts an active influence on the profile, height, and width of the confinement potential of both PIPPQW and IPPIPQW. The potential profile of IPPIPQW has been affected otherwise than PIPPQW for different ILF intensities. The nonlinear optical rectification, the second harmonic generation, and the third harmonic generation coefficients of PIPPQW and IPPIPQW could be altered in the energy range and the size of the resonance peak by rising the ILF intensity. By changing the parameter, it is conceivable to organize red or blue shift at the resonance peak positions of the nonlinear optical rectification, the second harmonic generation, and the third harmonic generation coefficients. The shift of the nonlinear optical rectification coefficient occurs when the difference between the ground and the second energy levels changes. According to the parameters used here, while for PIPPQW the spectrum of the resonance peak of the nonlinear optical rectification displays a blue shift with increasing ILF, this spectrum displays a red shift for IPPIPQW. The consequences can be valued in investigating new ways of changing the optical and electronic properties of semiconductor quantum wells.

Regulation of optical properties by applied external fields for a quantum well with Hulthen potential

In this present study, the effects of electric, magnetic, and non-resonant intense laser field (ILF) on the linear, third-order nonlinear, and total optical absorption coefficients (TOACs) and relative refractive index changes (RRICs) of GaAs quantum well, having Hulthen confinement potential, were theoretically investigated. In addition, the dependence of the nonlinear optical properties in the structure on the optical intensity of incident photon and the inverse relaxation time was also calculated. To do this research, firstly the energy eigenvalues and eigenfunctions of the structure were calculated by using the effective mass and envelope function approaches. By using these calculated subband energy levels and wave functions belonging to these levels, the nonlinear optical properties of the system were obtained via the iterative method, within the compact density matrix approach framework. The obtained numerical results show that the optical properties of the considered system depend on the externally applied fields. With the applied external electric and magnetic field, the peak positions of TOACs and RRICs shift to higher energies, and the peak magnitudes increase. The high-frequency ILF applied to the structure shifts the peak positions of TOACs and RRICs initially towards higher energies and then towards lower energies and their peak sizes increase. These results show that the optical properties of the system can be adjusted purposively by changing the magnitude of applied external fields.

The non-resonant intense laser field effects on the binding energies and the nonlinear optical properties of a donor impurity in Rosen–Morse quantum well

The non-resonant intense laser field effects on the binding energies and the nonlinear optical properties of a donor impurity in Rosen–Morse quantum well

Combined effects of electric, magnetic, and intense terahertz laser fields on the nonlinear optical properties in GaAs/GaAlAs quantum well with exponentially confinement potential

Combined effects of electric, magnetic, and intense terahertz laser fields on the nonlinear optical properties in GaAs/GaAlAs quantum well with exponentially confinement potential

Intensity-dependent nonlinear optical properties in an asymmetric Gaussian potential quantum well-modulated by external fields

In this paper, the effects of external electric, magnetic and non-resonant intense laser fields on the nonlinear optical rectification (NOR), second-harmonic (SH), and third harmonic (TH) generation in a GaAs quantum well with asymmetrical Gaussian potential are theoretically investigated. Firstly, the energy eigenvalues and eigenfunctions of a single electron confined in the structure are obtained by using the diagonalization method within the framework of the effective-mass and parabolic band approaches. Then, using these energy eigenvalues and eigenfunctions, expressions derived within the compact density matrix approximation have been employed to calculate the coefficients of the nonlinear optical response in the structure. The obtained simulation results show that the influence of the external fields leads to significant changes in the coefficients of nonlinear optical rectification, second and third harmonic generation in the system. As a result, it has been seen that the amplitude and position of the peaks of nonlinear optical rectification, second and third harmonic coefficients can be controlled by changing the applied external fields.

Laser Dressed Magnetic Polaron In Semimagnetic Core/Shell Nanostructure

The combined effects of magnetic and intense laser fields on the properties of the ground state exciton in semimagnetic Cd0.7Mn0.3Te/CdTe Core/Shell Nanostructure (CSN) are analyzed using the variational method in the effective mass approximation. The magnetic field of 5 to 20 T, a laser with the frequency of 10 THz and its intensity ranging from 0.44 to 7.11 μW nm−2 are considered as external perturbing fields. The evolution of Exciton Magnetic Polaron (EMP) in response to the external fields is explored via Magnetization (M) and Zeeman energy shift (∆EZE). The variation in binding energy (BE) of an exciton, M and ∆EZE are examined for different shell widths, magnetic and laser fields. The laser-induced diamagnetism due to the dressed energy state of carriers reduces the polarization of EMP. Similarly, the external magnetic field reduces the exchange interaction between carriers and weakens EMP. The combined effect of perturbing fields on an EMP will give an insight on controlling the performance of magneto-optic devices.

Optical properties of a GaAs quantum well with new type of hyperbolic confinement potential: Effect of structure parameters and intense laser field

In this present study, we have investigated theoretically the effect of structure parameters (η and κ) and high-frequency intense laser field (ILF) on the linear and nonlinear optical properties of a GaAs quantum well (QW) with new type of hyperbolic confinement potential. Within the framework of the effective-mass and parabolic band approximations, we have computed the confined subband energy levels and their corresponding densities of probability by using the diagonalization method. Besides, we evaluated the total optical absorption coefficients (TOACs) and total refractive index changes (TRICs). The obtained numerical findings show that an increase of the η (κ) structure parameter causes an increase (decrease) in amplitude in TOACs and a blue (red) shift of the resonance energy spectrum. In addition, with the increase of the ILF, the resonance energy spectrum shifts to blue, while the amplitude of TOACs (TRICs) increased (decreased). We think that the obtained these results can be useful in the design of new device’s generation employed in optoelectronic domain.